Andrea Cavallini

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It has been observed that voltage waveforms generated by power electronic converters may affect significantly the reliability of electric motor insulation. Since partial discharges are considered to be the main cause of the reliability loss, new enamel insulations for magnet wires are being developed in order to withstand better stress amplification. The(More)
Applications of a new methodology, aimed at the identification of defects occurring in insulation systems of HV apparatus and based on partial discharge (PD) measurements, are presented in this paper. This methodology relies upon the digital acquisition of a large amount of PD pulses and separates the acquired pulses into homogeneous subclasses. Signal(More)
This article is the first of a series of three that examines the correlation between off-line and on-line measurements on Type I random-wound motors. The off-line tests reported in this first article were carried out according to IEC 60034-18-4 to demonstrate that they are PD free under impulsive voltage conditions.
This paper represents the second part of a two-part article reviewing the state-of-the-art of probabilistic aspects of harmonics in electric power systems. It includes tools for calculating probabilities of rectangular and phasor components of individual as well as multiple harmonic sources. A procedure for determining the statistical distribution of(More)
Partial Discharge (PD) off- line and on-line measurements are required to prevent early failures on low voltage induction motors fed by inverter drives. Conventional methods use commercial Digital Scopes to visualize simultaneously the waveform of the applied impulsive voltage and the acquired PD pulses, as well as appropriate solutions to attenuate power(More)
A new technique for partial discharge (PD) source location in cable systems is presented in this paper. Such technique, here referred to as amplitude-frequency (AF) mapping, is based on the influence of attenuation and dispersion phenomena on PD pulse time and frequency characteristics. A comparative evaluation with other two well-known location techniques,(More)
This paper reports and discusses qualification and type test procedures for random wound motors as specified in IEC Technical Specification 60034-18-41. Since laboratory tests dealing with off-line partial discharges measurements followed by life tests showed that motors qualified as good can fail in very short times, an extensive investigation on the(More)
An investigation on partial discharge (PD) propagation in power cables is carried out in this paper with the aim of inferring limits for PD detection as a function of the distance between PD source and detector. Although this problem has not an exact solution unless noise levels are not specified, useful information concerning detectability and error in(More)
We report the results of an experimental study on the radiation hardness of 4H-SiC diodes used as alpha-particle detectors with 1 MeV neutrons up to a fluence of 8times10<sup>15</sup> n/cm<sup>2</sup>. As the irradiation level approaches the range 10<sup>15</sup> n/cm<sup>2 </sup>, the material behaves as intrinsic due to a very high compensation effect and(More)
This paper deals with the analysis of leakage current and phase angle characteristics of porcelain and silicone rubber insulator in order to develop a better diagnostic tool to identify the pollution severity of outdoor insulators. In this work, laboratory based pollution performance tests are carried out on porcelain and silicone rubber insulator under ac(More)